Methods for testing impurity content in a precious metal

ABSTRACT

A precious metal testing apparatus and methods adapted to analyze impurities in a precious metal test sample is described. The testing apparatus contains a test probe that has a replaceable portion and that is connected to a meter to measure resistance. The replaceable portion contains or forms a reservoir that includes at least one electrolyte component, a conductive member, and a fibrous tip. The electrolyte component is fluidly associated with a fiber tip and the conductive member contacts an electrical contact located outside the reservoir. Methods of testing and instructions regarding such methods are also included.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/546,307 filed Aug. 24, 2009, now pending, the contents of which arehereby incorporated herein by express reference thereto.

TECHNICAL FIELD

Methods adapted to test the impurity content of a precious metalcomponent and methods of assembling a replaceable cartridge component ofa testing apparatus. More particularly, the methods of assemblinginclude replaceable cartridges and the replacement of cartridges.

BACKGROUND OF THE INVENTION

Due to their chemical and physical properties, precious metals areincreasingly used in a variety of industries, including jewelry, art,coinage and exchange, fuel cells, man-made fibers, computers and otherelectronics, medicine and pharmaceutical products, and manufacturing.The unique properties of precious metals, along with their relativescarcity, dictate a high demand and value in the marketplace. Alloying aprecious metal with one or more other metals or non-metals, or platingor washing an article with a precious metal to increase aestheticappearance is often done to reduce expense but can result in non-uniformdistribution of precious metals throughout an article and articles ofdubious provenance are often poorly prepared. This can often alterproperties of such objects, and can be particularly detrimental to thefunctioning of articles that will be used for functional purposes beyondmere aesthetic appearance, such as noted above. It can also affect eventhe value of aesthetic articles, such as jewelry, art, and coinagedepending on the impurity content present. Determining the compositionof precious metallic samples and items accurately and quickly, whileminimizing the alteration of the sample in the process, is desirablewhen evaluating the sample for potential usefulness and pricing.

There are some long-standing analytical techniques currently availableto determine the nature, content and components of items that containprecious metals. Some analytical methods use an electrochemical processto evaluate the purity of precious metals. For example, U.S. Pat. No.4,799,999 teaches a method whereby the specimen is wetted with anelectrolyte, a small current then anodizes the surface of the specimenfor a metered period of time, a sensing device is then applied to thecharged surface and observes the potential decay, which is theninterpolated with empirical data to determine the karat quality of agold alloy.

As another example, U.S. Pat. No. 5,218,303 concerns a method where acontrolled amount of electrolyte is deposited on a sample of preciousmetal alloy, an electrode is placed in contact with the sample andelectrolyte through which an electric current is applied to create anelectrolyte paste. As the current decays to an asymptotic level, asecond and third pulse of electric current are applied and the measuredelectrical conductance is compared to a table of standards.

Another testing device includes a handheld applicator to apply a testingsolution. For example, U.S. Pat. No. 6,103,194 concerns a handheldapplicator for testing metallic items and includes a housing thatsurrounds an insert containing a reservoir with a testing chemical andan applicator, which applies the testing chemical to the surface of themetal.

U.S. Pat. No. 5,888,362 concerns a handheld probe having an electrodeembedded in an electrolyte in a reservoir of the probe and arranged toconduct electrically with the sample through the electrolyte and afibrous tip. A battery is coupled to a calibration potentiometer and thesample in circuit to form a galvanic cell.

These devices have one or more limitations that have prevented them fromgaining widespread acceptance in the industry. Thus, an improved testingdevice and methods according to the invention described below have beendesired to expedite economical testing of precious metal objects.

SUMMARY OF THE INVENTION

The invention encompasses a precious-metal testing apparatus adapted toanalyze an impurity content of a precious metal sample, which includes atest probe having a probe end and a connection end, wherein the testprobe includes a housing and a cartridge including a conductive member,a supply of an electrolyte component, and a casing retaining theelectrolyte component, a portion of the conductive member, and an end ofa fibrous tip at the probe end in fluid communication with theelectrolyte component, wherein the cartridge is retained by the housing,and wherein the fibrous tip is electrically conductive when a sufficientamount of the electrolyte component is present therein, along withpreferably a meter adapted to measure an electrical resistance of aprecious-metal sample through the test probe, an electrical connectionthat electrically associates the conductive member of the cartridge,which extends through an end thereof opposite the probe end, with anexternal conductive component that extends to the meter, wherein theelectrical connection is located outside the casing that contains theelectrolyte component.

In one embodiment, a portion of the test probe is replaceable so as topermit replenishment of the supply of the electrolyte component. Inanother embodiment, the conductive member includes palladium, silver, ora mixture thereof In another embodiment, the test probe is releasablyconnected to the external conductive component. In a preferredembodiment, the housing includes a closed position to retain thecartridge and an open position configured to release the cartridge forreplacement thereof. In yet another preferred embodiment, the housingincludes a plurality of pieces that can threadedly couple to form theclosed position and uncouple to attain the open position.

In another embodiment, the fibrous tip is at least substantially free,or entirely free, of an epoxy. In another embodiment, the fibrous tip isat least substantially free, or entirely free, of any resin that hardensthe tip over time or through exposure to the atmosphere or theelectrolyte component. In one preferred embodiment, the test probe andelectrically conductive portions thereof are at least substantially,preferably entirely, corrosion resistant. In yet another embodiment, theapparatus further includes an integrated file associated with the testprobe for minimizing or removing a contaminant portion from the testsample.

The invention also encompasses a method for analyzing an impuritycontent of a precious metal sample, which method includes associating anelectrically conductive zone of a portable testing device with thesample, wherein the electrically conductive zone is detachable from theremainder of the testing device is replaceable, measuring the electricalresistance of the test sample, and comparing the measured resistance toa standard value of electrical measurements including at least one ofthe same type of precious metal to determine the impurity content of thesample. In one embodiment, the method further includes displaying themeasured resistance to a user. In another embodiment, the method furtherincludes removing at least a portion of a contaminant component from asurface of the sample before measuring.

The invention further encompasses a replaceable, impurity contenttesting cartridge sized and configured to fit a precious metal testprobe that includes a non-conductive casing including an electrolytecomponent present in an amount sufficient to conduct electricity througha portion thereof, a conductive member electrically associated with theelectrolyte component and oriented at least partly along a length of thecasing so that a portion of the conductive member extends through thecasing so as to minimize loss of the electrolyte component, and anelectrically non-conductive fiber tip at least partially contacting theelectrolyte component through an aperture in the opposite end of thecasing, wherein the fiber tip is electrically conductive when asufficient amount of electrolyte component is absorbed therein, andwherein the portion of the conductive member that extends through thecasing is adapted for electrical connection in an environment that is atleast substantially free, preferably entirely free, of electrolytecomponent.

In one embodiment, the replaceable cartridge further includes a fibrousmaterial that at least partially surrounds the conductive member in thecasing to inhibit the loss of electrolyte component from the casing. Inanother embodiment, the electrically non-conductive fiber tip includes aplurality of at least substantially parallel elongated fiber portionspressed together. In a preferred embodiment, the plurality of fiberstrings include an acrylic component. In another embodiment, differentacrylic components can be used in different fiber strings.

In yet another embodiment, the conductive member includes palladium,platinum, or silver, or a combination thereof In a preferred embodiment,the conductive member includes a first metal in a core layer and asecond, different non-corrosive metal that surrounds the first metal toinhibit or prevent contact between the core layer and the electrolytecomponent in the casing. In another preferred embodiment, the cartridgefurther includes an electrical contact that includes the same materialas the conductive member and is electrically associated therewith.

In a further embodiment, the electrolyte component includes an aqueousacidic solution. In a preferred embodiment, the aqueous acidic solutionincludes at least one of ammonium chloride (NH4Cl), hydrochloric acid(HCl), nitric acid (HNO3), or any combination thereof. In a morepreferred embodiment, the aqueous acidic solution includes ammoniumchloride (NH4Cl) and distilled water, preferably as a solution ofsaturated ammonium chloride.

The invention also encompasses a method for repairing the precious-metaltesting device of claim 5 which includes adjusting the housing of thetest probe into the open position, removing the replaceable cartridgefrom the test probe, inserting a replacement cartridge within thehousing, and returning the housing to the closed position so as toretain the replacement cartridge.

The invention further encompasses a set of instructions to carry out anyof the methods discussed herein, along with the precious-metal testingdevice, the test probe, or the replaceable cartridge, as applicable,operably associated with the instructions.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure can be better understood from the followingdetailed description when read with the accompanying figures. It isemphasized that various features are not drawn to scale and are usedonly for illustrative purposes. In fact, the dimensions of the variousfeatures may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a sectional view of a replaceable cartridge accordingto the invention;

FIG. 2A illustrates a sectional view of a tip housing in relation to aconductive member which is associated with an electrical contactaccording to the invention;

FIG. 2B illustrates an elevation view of an electrical contact accordingto the invention;

FIG. 3 illustrates a sectional view of an outer casing that surrounds areservoir for electrolyte component and at least a portion of the tipaccording to the invention;

FIG. 4 illustrates a sectional view of a reservoir, a conductive memberand electrical contact in a replaceable cartridge according to theinvention;

FIG. 5 illustrates a sectional view of an exemplary electricalconnection and a seal to be disposed at an end of a cartridge that isopposite a tip according to the invention;

FIG. 6 illustrates a sectional view of a housing that surrounds and canretain a cartridge and a releasable electrical connection according tothe invention;

FIG. 7A illustrates a sectional view of the test probe with a portion ofthe housing that partly forms the closed position, without thereleasable electrical connection, according to the invention;

FIG. 7B illustrates a sectional view of the probe end of a test probewith a portion of the housing that partly forms the closed position,without the fibrous tip, according to the invention; and

FIGS. 8A and 8B illustrate three dimensional views of the assembled testprobe, according to varying embodiments of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The apparatus and methods described herein facilitate more accuratetesting of an impurity content in and on precious metal object(s) via astable test probe that contains a supply of an electrolyte componentthat includes at least one electrolyte, and that resists corrosion overan extended period of time. A portion of the test probe is replaceableto replenish the supply of electrolyte(s), and this can be a replaceablecartridge disposed at least partially within the test probe or it can bethe entire test probe. The test probe contains a probe end that contactsa precious metal object to be tested and a connection end that includesor forms an electrical connection to an electrical meter. The cartridgecan form a portion of the reservoir along with the tip housing andconductive member. Preferably, however, the cartridge contains aself-contained reservoir that includes the supply of the electrolytecomponent that is sufficient to conduct electricity from a tip at theprobe end to a conductive member disposed in or adjacent to thereservoir, which conductive member conducts electricity to theconnection end of the test probe. The test probe can preferably bereleasably electrically connected to a conventional meter. A portion ofan outer surface of the replaceable cartridge can be electricallyassociated with the meter so as to minimize corrosion at the electricalconnection.

The electrical conduction between two different precious metals orprecious metal-containing alloys, or a combination thereof, one part ofthe test probe and the other being the test sample, can be compared,measured and quantified by a conventional meter as described elsewhere(See, for example U.S. Pat. No. 5,888,362, the contents of which areincorporated herein by express reference thereto regarding operation andconstruction of suitable meters).

The configuration and replaceabilty of the test probe or a portionthereof allows for greater variability in the type and size of preciousmetal(s) to be tested because different size test probes can be used.Additionally, this can advantageously provide increased portability andeven facilitate replacement when the supply of electrolyte(s) is in needof replenishment. By arranging the electrical connection of theconductive member to a connection end of the cartridge to electricallyconnect to the meter outside the reservoir, this can and preferably doesminimize or avoid corrosion that typically occurs inelectrolyte-containing test devices. An exemplary embodiment of theinvention is discussed below.

FIG. 1 illustrates a sectional view of an embodiment of a replaceablecartridge 1 that is placed inside a housing of the test probe. Thereplaceable cartridge 1 includes at least a reservoir 20 that containsat least one electrolyte and preferably, a fibrous material associatedtherewith, a conductive member 15 that is operably and electricallyassociated with a tip 5 at the probe end and is connected to a contact30 at the connection end, along with a tip housing 10 adapted toposition the tip 5 properly and an outer casing 25 that at leastsubstantially contains the reservoir 20 and is attached to the tiphousing 10.

The electrolyte component is typically a solution in the reservoir 20.The electrolyte component can include any suitable electricallyconductive liquid material that can be dispensed through the tip, but istypically acidic. The electrolyte component is preferably at least oneof ammonium chloride (NH₄Cl), hydrochloric acid (HCl), nitric acid(HNO₃), or any combination thereof. An exemplary electrolyte componentis a solution formed by adding ammonium chloride (NH₄Cl) into distilledwater until the solution is saturated. Typically, under ambientconditions (e.g., 68° F. and atmospheric pressure), this will be about40.8% by weight ammonium chloride and about 59.2% by weight distilledwater. Different concentrations will be preferred for use in differenttemperatures, elevations, and if a different electrolyte component isincluded, each of which can be determined by one of ordinary skill inthe art, particularly in view of the guidance provided herein. Thecasing (or housing) is preferably at least substantially, or entirely,free of a gel.

A plurality of the fibers in the reservoir 20 are preferably oriented insubstantially the same direction, or the same, direction. A preferreddirection for the plurality of fibers is at least substantiallyparallel, or parallel, to one another. In this regard, “substantially”refers to an angle between two fibers of less than about 30 degrees,preferably less than about 15 degrees, and more preferably less thanabout 5 degrees. Preferably, the fibers are oriented longitudinally inthe direction of the fiber tip 5 and the contact 30 at the other end ofthe cartridge 1. Preferably, the directional fibers in the tip 5 areprepared by pressing a plurality of smaller fibers together to form atip of desired thickness or diameter. The fibers can be made of any of avariety of natural or synthetic fibers or combinations thereof availableto those of ordinary skill in the art. The fibrous tip 5 is at leastsubstantially free, and preferably entirely free, of epoxy or resin.Preferably, the tip 5 is at least substantially free, preferablyentirely free, of any resin that increases the hardness of the tip overtime, or upon repeated exposure to the atmosphere or the electrolytecomponent.

Preferably the fibers used to form the tip and the fiber material in thereservoir 20 include silk or corn silk. The tip and fiber material inthe reservoir 20 are independently selected and can be the same ordifferent. In one embodiment, it is preferred that these are the same.The tip and fiber material in the reservoir can be integrally formed tofacilitate wicking the electrolyte component from the reservoir 20through the tip 5 to the test sample.

The reservoir 20 is in contact with at least a portion of theelectrically non-conductive absorbent fiber tip 5. Suitable fiber tips 5can preferably include acrylic fiber material, such as that commerciallyavailable from Teibow of Japan (e.g., Product No. TCE470C) or PorexTechnologies of Fairburn, Ga. A portion of the end of the fiber tip 5opposite the probe end extends into the reservoir 20. The portion can bethe whole or only a part of the tip. The tip housing 10 functions as a“spacer” to help properly position the fiber tip 5 within the tiphousing 10 so that the end is in alignment and in fluid communicationwith the reservoir 20. The electrolyte component present in thereservoir 20 can be absorbed at the end of the fiber tip 5 by capillaryaction. Once an amount of the electrolyte component is absorbed by thefiber tip 5, the probe end (i.e., the exposed end that contacts the testsample) of the fiber tip 5 can be positioned adjacent or preferablycontacting the test sample to complete an electrical circuit so that areading on the meter can be obtained. The fiber tip 5 is partiallyencased in the tip housing 10 so as to help manage only a sufficientflow of the electrolyte into the fiber tip 5, as excessive flow willrender the test probe inoperative sooner as the electrolyte component isdepleted faster. The tip housing 10 can be made of any non-conductivematerial, in one embodiment preferably a plastic material and morepreferably a polymer such as polypropylene, polyethylene, or acombination thereof. A suitable polypropylene is commercially availablefrom Lyondellbasell (e.g. Product Pro-fax™ PD626), which can be shapedas desired through conventional molding, injection, or another formationtechnique available to those of ordinary skill in the art.

The reservoir 20 is at least partially sealed, and preferably entirelysealed to minimize or avoid loss of electrolyte component except throughthe tip during operation of the test apparatus. In fact, an operativelyassociated covering 65 (as shown in FIGS. 8A and 8B) can be used withthe test probe and used to cover the tip when not in use to furtherrestrict loss of electrolyte component. Preferably, the reservoir can bedefined by a casing 25 that extends around a zone containing theelectrolyte component. Preferably, the reservoir 20 can be containedprimarily by the outer casing 25 in a zone that is any three-dimensionalshape including one that is substantially or entirely cylindrical,spherical, oblong, oval or capsule-shaped. Preferably, the zone is atleast substantially cylindrically shaped, or cylindrically shaped, so asto best fit a user's grasp like a writing implement or dental tool. Thesubstantially cylindrical shape can be, for example, like a pencilhaving about five to nine facets around the circumference of thecylinder. Whether or not the zone has circular cross-sections of similardiameter, the housing or a portion thereof (discussed below) can bearranged to have the desired shape and have internal projections tomatch and retain the outer casing 25 to help retain it in a fixedposition relative to the other components in the test probe. Thereservoir 18 and the casing 25 can be independently selected from anyavailable substantially or entirely non-conductive material, preferablya glass or a plastic component of one or more glass or plasticmaterials. A plastic component is preferred as it is less likely toshatter, however, it must be a suitable plastic with low moisturemigration potential to inhibit drying of the electrolyte component. Morepreferably, the casing 25 includes polypropylene, polyethylene, or acombination thereof. Suitable material is commercially available from,for example, Filtrona Porous Technologies of Colonial Heights, Va. Thecasing 25 preferably is sized and shaped to match the reservoir 18. Inone embodiment, the casing 25 has at least one aperture, and preferablyonly one aperture, at the probe end to facilitate flow of theelectrolyte component into the fiber tip 5. In another embodiment,multiple tips (not shown) can be used and the casing 25 would havemultiple apertures (not shown) at the probe end sized and dimensioned topermit these multiple tips to extend therethrough. Thus, referenceherein to a “tip” could also be understood to refer to multiple suchtips, although a single tip is preferred in most embodiments. To a user,however, the multiple tips might be sufficiently small and arrangedsufficiently closely together that they would appear to be a single tipexcept upon closer examination or using magnifying equipment. Theelectrolyte component can then be repeatedly dispensed as needed whenthe test probe is used to contact different precious metal test samples.In each case, the tip housing 10 is preferably sized and dimensioned toclosely fit the tip 5 so as to minimize excess space around the tip thatcould facilitate the undesirable escape of electrolyte component orcorrosive gases generated by the electrolyte component in the tip. Thus,the tip housing 10 is preferably sized to have a chamber only largeenough to fit the tip 5 and so that the tip 5 at least substantially,preferably entirely, fills the chamber in the tip housing 10. The tiphousing 10, and associated tip cap 55, however, can have a similar ordifferent shape than that of the adjacent and complementary casing 25and housing 45 that surround the reservoir 20. As seen in FIGS. 8A and8B below, the housing 45 can be cylindrical but recessed from theoperatively associated tip cap 55 and tip covering 65. The tip 5 willpreferably contain a portion that projects beyond an end of the tiphousing 10 and in towards and into the reservoir. This projection 12 inFIG. 2A (discussed below), preferably is open on a portion of theprojection to permit fluid communication of the electrolyte componentwith the tip 5.

Through the reservoir 20 extends a conductive member 15 that helpsconduct electricity between the meter and the test sample. Theconductive member is typically a corrosion-resistant metal componentbecause it must contact the electrolyte component to exchange electricalcurrent with the tip. The conductive member can take any suitable shape,but is preferably primarily an elongated bar, strand, wire, tube, or thelike. The conductive member 15 is preferably palladium, platinum, orsilver, or a combination thereof, and preferably palladium or silver, ora combination thereof. In a preferred embodiment, the conductive member15 includes a strand of conducting palladium such as that commerciallyavailable from Union City Filament Corporation of Ridgefield, N.J. It isalso possible to make the conductive member 15 of one or more layers. Itcan be formed of any conductive material(s) as a core layer, or evennon-conductive material as a core layer that forms a backbone that iscompletely surrounded by, or plated with, one or morecorrosion-resistant materials, preferably one of the above-noted metals,or a combination thereof, to minimize or avoid any conductive core layercontact with the electrolyte component. A conventional, less expensiveconductive material such as copper, and more preferably nickel-platedcopper, is typically used at the connection end of the test probe toconnect with the conventional meter because of cost considerations, buta change from a corrosion-resistant metal component in the conductivemember to a more cost efficient conductor is preferably achieved betweenthe conductive member at least partly disposed the cartridge and themeter. This connection is preferably arranged to minimize or avoidcontact with the electrolyte(s) and any gas generated therefrom. Thus,the connection preferably occurs between a conductive portion of thecasing 25 or the test probe (not shown), and a conventional wire outsidebut adjacent and in electrical communication with the cartridge. Theconnection can be a banana clip or plug, such as that available fromPomona Electronics of Everett, Wash. (e.g., Product No. 72930), made ofany suitable material known to those of ordinary skill in the art,preferably copper and more preferably nickel plated copper, or any othersuitable device available to those of ordinary skill in the art tofacilitate connection of the two distinct types of conductive materialsin the conductive member and the electrical connection from the testprobe to the test meter.

The conductive member 15 preferably contacts the electrical contact 30so as to transmit electrical signals to and from the meter. Theconductive member 15 can be doubled up, looped, braided, or placed inany other suitable arrangement at the end of the cartridge adjacent theelectrical contact 30 to help ensure sufficient electrical conductivity.Preferably, the arrangement of the conductive member 15 will helpminimize the impact of the corrosive environment in the cartridge 1 onthe conductive member 15. This arrangement can provide a compressionspring-like action to facilitate maintaining the conductive member 15 intouch with the electrical contact 30. The conductive member 15 may touchthe sides of the casing 25 without affecting the readings from thesample. The replaceable cartridge 1 is arranged inside the housing ofthe test probe, to be described below. It should be understood that theconductive member 15 could exit the casing 25 at any point, such as byextending along a radius of the casing 25 and through a side location ofthe casing 25, at which point it could extend longitudinally towards theconnection on the outside of the casing 25 but inside the housing. Infact, the connection with the conventional wire that leads to the testercould occur at any location along the outside of the casing, butpreferably it is positioned as depicted at the end of the casing 25opposite the probe end where the tip 5 is located.

With reference to FIG. 2A, the conductive member 15 can extend theentire length of the reservoir 20 from the contact 30, can terminate inthe reservoir 20 in the form of an at least partial loop (see FIG. 4) ora complete loop (not shown), or can terminate short of the tip so longas it extends along at least about seven-eighths the distance of thelength of the reservoir 20 from the contact 30. In another embodiment,the conductive member can actually contact the end of the tip 5, or evenextend into a portion of the tip 5. In the depicted embodiment, the tiphousing 10 includes a projection 12 that can be used to help align thetip 5 and tip housing 10 when they are seated against the remainder ofthe cartridge. The projection 12 typically includes at least oneaperture (not shown) that pen nits fluid communication of theelectrolyte component between the reservoir and the tip 5.

With reference to FIG. 2B, the electrical contact 30 is preferablylocated outside of the casing 25 but remains in electrical contact withthe conductive member 15 or a similar material. The contact 30 depictedin various figures including FIG. 1 is therefore preferably made of thesame material as the conductive member 15 as to the portion inside thecasing that might contact electrolyte component or off-gases generatedtherefrom, but preferably a non-conductive material separates theconductive member 15 and the contact 30. Preferably the casing 25 isintegrally formed and the conductive member 15 is inserted in anaperture 32 sized only sufficiently to permit the conductive member 15therethrough so as to minimize loss of electrolyte component. Theelectrical contact 30 can take any shape so long as it remainselectrically conductive, is in contact with the conductive member 15 andfits within the external housing 45 of the test probe. The electricalcontact 30 can be made of substantially or entirely the same material asthe conductive member 15 or it can be made of the same or similarmaterials adapted to electrically connect the test probe to the meter,preferably including copper and more preferably nickel-plated copper,such as that commercially available from Braxton Manufacturing Co., Inc.of Watertown, Conn. While such material can be independently selected,in one embodiment it is preferred that the material be the same as theconductive member 15 to minimize corrosion. As further discussed below,the contact 30 must be electrically associated with the top contact 35(shown in FIGS. 5-6) of the external wire 50 (FIGS. 5-6) so that currentcan pass between the reservoir 20 and the external wire 50 associatedwith the meter.

FIG. 3 depicts just the casing 25 that is open at the probe end and inthe depicted embodiment is open at the contact/connection end oppositethe probe end. The casing 25, along with the tip housing 10 andoptionally the contact 30 fowl the reservoir 20 that contains theelectrolyte component. In a non-depicted embodiment, the casing 25 issealed at the contact 30 end except an aperture 32 for the conductivemember 15 of FIGS. 1 and 2A to extend through.

FIG. 4 depicts an embodiment showing the reservoir portion 18 of thecartridge. The reservoir portion 18 includes an electrolyte component 20and a conductive member 15, which in this embodiment terminates in aless than complete loop at the probe end and forms a circular plane atthe opposite end. A casing 25 (shown in FIG. 3) can have the reservoirportion 18 and an aligned, adjacent tip Sand tip housing 10 (shown inFIG. 2A) disposed therein to form a replaceable cartridge.

FIG. 5 better illustrates an exemplary electrical connection associatedwith the contact 30. The electrical connection contains a secondelectrical contact 35 connected to an external wire 50 that connects tothe meter (not shown). Preferably, it also is associated with a gasket40 that can be formed of a non-conductive component, such as a rubbercomponent, to minimize or avoid loss of current or interference to thecurrent. The second contact 35 can be made of the same or similarmaterials as the contact 30 or it can be made of the same or similarmaterials adapted to electrically connect the connection end to themeter, preferably copper and more preferably nickel-plated copper, suchas that commercially available from Boker's, Inc. of Minneapolis, Minn.The second contact 35 can have the same or a dissimilar shape as thecontact 30 provided that there is sufficient electrical communicationtherebetween for current flow between the conductive member 15 and themeter. For example, the first and second contacts 30 and 35 can besoldered together, or they can each be planar or substantially planarsurfaces that are adjacent to each other preferably with pressureapplied by the housing (not shown in FIG. 5) urging the two contactsinto closer contact. In a preferred embodiment, a banana connector isused to connect the external wire 50 from the meter to the secondcontact 35 of the test probe. The electrical connection between the testprobe and the meter may be released so as to minimize electrical hazardswhen changing the replaceable cartridge, or to permit replacement of theentire test probe. Preferably, the external wire 50 is acopper-containing wire although any suitable conventional wire orelectrical connector may be used as the external wire 50 to connect themeter with the second contact 35. The connection between the externalwire 50 and the second contact 35 is distal (i.e., opposite and away)from the electrolyte and outside of the reservoir 20, so as to minimizeor avoid corrosion of the electrical joint between the conductivemember, 15 and the external wire 50 and at the contact 30 and secondcontact 35.

FIGS. 6, 7A and 7B illustrate an embodiment of portions associated withthe housing 45 into which the replaceable cartridge 1 and secondelectrical connection 35 are placed. In a preferred embodiment, thehousing 45 includes a top cap 60, a tip cap 55 and a housing body 45.The housing is made of any electrically non-conductive material, such asa plastic component or a glass, or any combination thereof, preferably aplastic polymer such as polyethylene or polypropylene, or a combinationthereof. Although not depicted, the housing 45 can be integrally formedwith either the top cap 60 or the tip cap 55, since the cartridge 1 canbe inserted from either end of the housing body 45. When the top cap 60is integrally formed, the external wire 50 is releasably connectedthrough a standard plug-in electrical connection once the housing 45 isassembled. As seen in FIG. 6, the second electrical connection 35associated with the external wire 50 is located inside the housing,adjacent to or even within the zone formed by the top cap 60 of thehousing 45. The top cap 60 can be connected to and released from thehousing body 45 and optionally and preferably the second electricalcontact 35, and this joining and separation to the closed and openpositions of the housing 45 can be achieved by any suitable techniqueavailable to one of ordinary skill in the art, such as threading, pushand turn, spring, or slide mechanism. In addition, or alternatively, thetip cap 55 can be releasably attached to the housing body 45 in anymanner that is independently selected from those available, such asdescribed herein for the top cap 60. The tip cap 55 has an aperture forthe top of the fiber tip 5 to fit into so that the electrolyte componentcan be dispensed into the fiber tip 5 that is then placed in contactwith the test sample. Indeed, the tip housing 10 can be disposed in thetip cap 55 so as to seat the tip 5 associated with the cartridge 1 intothe tip cap 55 so it extends through the aperture and helps align thetip cap 55 as it is moved into a closed position with the remainder ofthe housing 45. An additional covering can be formed to fit over theexposed portion of the fiber tip 5 so as to avoid drying out of thefiber tip 5, or the tip cap 55 can be sealed at the tip end and usedonly for sealing the tip where the housing 45 is already formed so as tocontain its own tip housing 10. The additional covering can also bereleasably attached to the housing through any suitable attachmentmechanism as discussed herein.

FIGS. 8A and 8B illustrate an embodiment of the test probe when fullyassembled. The housing 45 can take any three-dimensional shape includingone that is partially, substantially or entirely cylindrical, spherical,oblong, oval or capsule-shaped. Preferably, the housing 45 is shapedsimilarly to the component parts that it contains to facilitate thecomponents functioning as described herein. In the depicted embodiment,the housing 45 has a tapered, or recessed, region so as to facilitate auser's grip on the test probe, such that it is partially cylindricalwith a recessed portion. As shown in the embodiment depicted in FIG. 8B,the top cap 60 at the connection end is slightly tapered and the portionof the tip cap 55 is tapered inwards towards the probe end. The covering65 that is operatively associated with the tip cap 55 and/or the housing45 can be made of any non-conductive material, in one embodimentpreferably a plastic and/or rubber material. More preferably, thecovering 65 includes a rubber material, such as that commerciallyavailable from McMaster-Carr of Chicago, Ill. (e.g., Product No.4777A14), with a polypropylene encasement that is operatively associatedwith the tip cap 55 and/or the housing 45.

The housing (including any separate but joinable tip or top cap andcovering), the replaceable cartridge and preferably the secondelectrical connection encompass the test probe. The test probe isportable and able to be carried in a pocket or by hand to the testingsample or adjacent a meter. An integrated file may be attached to thetest probe by a clip or some other attaching device, or it may beattached to the adjacent meter body. The integrated file can be used tominimize or remove any coatings or platings that are present on the testsample, such as by scraping or scoring of the coating or plating toincrease electrical contact between the tip 5 of the test probe and theprecious metal sample to be tested.

The apparatus described herein tests the impurity content of preciousmetals, and it can advantageously do so across a wide range of impuritycontents. The apparatus is adapted to accurately measure purity of, forexample without limitation, gold test samples over a range of alloysfrom 6K to 24K gold, and will accurately and precisely read impuritycontent even if the sample is gold-plated or washed. These readings willpreferably remain accurate and precise until the electrolyte componentis depleted, because the apparatus is advantageously designed tominimize or avoid corrosion of its electrical connections.

For example, a replaceable cartridge with a reservoir containing asaturated aqueous solution of ammonium chloride (NH₄Cl) in distilledwater and a palladium wire, is placed inside the housing and the housingis placed in the closed position by threadedly interconnecting the tipcap and the housing body. The second electrical connection and top capare connected to the housing body (i.e., the housing) and thereplaceable cartridge. After grounding the electrical circuit,preferably by using either a grounding plate on the housing of the meteror a grounding wire, the fiber tip containing a sufficient amount ofelectrolyte component is placed on or adjacent to the test sample. Itshould be understood that the test sample must be placed on or in stablecontact with the grounding plate, or otherwise grounded using thegrounding wire, which can be attached to the sample by any availabletechnique, including without limitation an alligator clip or mini-visegrip, if the sample is too large to fit and remain in contact with agrounding plate associated with the testing apparatus or the associatedmeter body. When the moistened fiber tip is placed on the test sample,the current generated by the test sample is measured by the meter. Forexample, when testing a 24 carat (K) gold test sample, this is pure andno impurity content is present. The meter thus measures a low resistanceand therefore relatively high current. If the allegedly pure gold testsample contains impurities such as tin, nickel or bronze, or is plated,including a heavy gold wash plating, the meter will detect moreresistance and so less current will be registered by the meter. Whilethe meter cannot always clearly indicate the contents of the impurities,the increased resistance from a pure gold standard current clearlyindicates that a lower carat test sample is present (i.e. 18K, 14K or10K gold). When the sample is not pure initially, such as when thesample is 18K or 14K gold, the resistance level of a known 18K or 14Kgold sample can be tested or a reference standard checked in a standardtable, and then changes in resistance or current flow can show thepresence of additional unexpected impurity. Alternatively, the testingapparatus can be used to test the purity of other precious metals, suchas platinum or palladium.

Multiple applications and electrical readings can be obtained with asingle cartridge or test probe, which can last at least about threemonths, preferably at least about six months, and in one preferredembodiment at least about one year. Without being bound by theory, it isbelieved that this can surprisingly be achieved in part because of thecorrosion-resistant arrangement of components of the test probe and thearrangement of other aspects of the probe to extend the usable life ofthe tip. The length of stable readings from a given cartridge orreplaceable test probe will depend on various factors including use of acovering to seal the tip, direction of the test probe when storedbetween uses, length of use for each test, sample tested, temperature,pressure, etc. The apparatus of the invention, however, will lastsignificantly longer than conventional testing devices due to theirsurprising electrical contact arrangements, their general designincluding a fibrous tip, and the resultant reduced corrosion achieved bysuch an arrangement. Thus, by “substantially corrosion resistant” it ismeant that the electrical connections will resist corrosion and remainactive and precise (without false or significant imprecise readings suchas 0.1% errors or greater) over extended periods of time such as atleast about 3 months, at least about 6 months, at least about 9 months,and preferably at least about one year, or until such time as the testprobe requires replenishment of the electrolyte component.

The above-described apparatus is used to analyze the impurity content ofa sample of precious metal or an alloy thereof. The methods used toanalyze a precious metal sample are not particularly limited to onetechnique, manner or skill set. The conductive zone of the testingdevice, which is preferably portable, is associated or placed intoelectrical contact with the precious metal-containing sample. Theconductive zone, or region where conductivity occurs through electricalcontact between the sample and the testing device, preferably isdetachable from the rest of the testing device so as to ensure ease ofreplacement thereof. Once the conductive zone of the portable testingdevice is attached to the rest of the testing device, is in contact withthe sample, and current is able to flow through the conductive zone byuse, for example, of a grounding plate or wire as part of the conductivezone, the amount of resistance to that current as emitted by anyimpurities in the sample can be measured. This can be measured by anysuitable meter available to those of ordinary skill in the art,including a meter such as an ohmmeter. Preferably, the measuredresistance is displayed to a user through any format including, but notlimited to, electronic, print, digital, LCD or analog, or a combinationthereof, and can be stored electronically or in print for later review.In one embodiment, a portion of surface contaminants present are removedfrom the sample, for example by filing, washing or otherwise scratchingor scraping the surface of the sample, or a combination thereof, beforethe sample is contacted by the conductive zone of the testing device.This can advantageously increase the speed, convenience and accuracy ofthe testing device. In a further embodiment, a file can be integratedinto the body of the testing device such as part of the test probe orthe meter, so as to eliminate the need to carry multiple items fortesting in different locations.

The measured resistance can then be compared to a standard value ofelectrical measurements to more accurately determine the impuritycontent of the sample. In one embodiment, the measured resistance can becompared against a pure sample of that type of precious metal, against aknown sample having an expected level of impurity of that type ofprecious metal, against a reference standard for either, or the like. Inanother embodiment, the type of precious metal or alloy thereof is inputinto the testing apparatus to provide a more meaningful result in whichthe measured resistance is more readily compared against a pure sampleor another type of reference standard for that inputted type of preciousmetal or alloy thereof. In this embodiment, the display can thereforeindicate the level of impure content or the level of purity of thesample through well-known calculation(s) based on the measuredresistance, the inputted type of precious metal or alloy thereof, andbased on guidance herein as to the invention. In one embodiment of theinvention, the type of precious metal or alloy thereof is input into thetesting apparatus to provide a more meaningful result in which themeasured resistance is compared against a pure sample or another type ofreference standard for that inputted type of precious metal or alloythereof. In this embodiment, the display can therefore indicate thelevel of impure content or the level of purity of the sample throughwell known calculation based on the measured resistance, the inputtedtype of precious metal or alloy thereof and based on guidance herein asto the invention.

In one embodiment, the precious-metal testing device is able to bereadily repaired by an end-user rather than requiring a professionalwhen the test probe is depleted of sufficient electrolyte component,such as through lengthy or heavy use or leaking of the electrolytecomponent when a user does not use the preferred associated tipcovering. Replacement of the cartridge or test probe can also beachieved when a different cartridge containing a different electrolytecomponent or tip is desired, such as when the tip is smashed, soiled,hardened, or the like, or if certain electrolyte mixtures are determinedto work better for certain types of precious metal testing. The methodfor repairing the precious-metal testing device substantially includesopening the housing of the testing probe or of its component parts torelease the relevant component part that retains the electrolytecomponent, the tip, or the like. In a preferred embodiment, the housingdevice components are threadedly coupled to one another so as to enableseparation of the components upon twisting of the tip cap, top cap, orboth, of the housing. As noted elsewhere herein, in a preferredembodiment either the top cap or the tip cap are integrally formed withthe housing body, or are separately formed but only one needs to beremoved to proceed with the replacement of the electrolyte component.Once a portion of the housing is in the open position, the replaceablecartridge or casing inside the housing can be removed from the testprobe and a different replacement cartridge is placed within thehousing. The housing is then returned to the closed position, forexample without limitation by turning, twisting, pushing or pulling, ora combination thereof depending on the housing design, of its componentparts or a mechanism which then holds the component parts together inthe closed position. In one embodiment, the mechanism can be anymechanical item which releasably holds the components of the housingtogether, such as a switch, snap, a locking device or a securing device,or any combination thereof. In a preferred embodiment, the tip cap andtop cap of the housing are threaded so as to facilitate re-coupling ofthe housing portions to each other so as to retain the cartridge orcasing therein for use. In a preferred embodiment, a set of instructionsto carry out the replacement is associated with the precious-metaltesting device. Preferably, the instructions are tailored to the type ofinterconnections and fastener(s) the components of the housing contain.In another embodiment, instructions can be provided to carry out themethod of testing an impurity content in a precious metal-containingsample according to the invention, and are preferably provided with thetesting apparatus prepared according to the invention.

The cartridge, housing, or entire test probe can be readily replaced ormade replaceable if desired when the tip becomes soiled or smashed, orthe electrolyte component depletes so that an insufficient amount ispresent in the tip. Thus, in one embodiment, the housing body 45 is thecasing itself that contains the electrolyte component and a portion ofthe tip and a portion of the conductive member. Thus, the term“replacement cartridge” can include without limitation any one of thefollowing: (a) the entire test probe up to the external wire; (b) theentire test probe except for the external wire and the second electricalconnection; (c) the entire test probe including the housing and all thecomponents contained therein, provided that the housing does not includethe external wire, the second electrical connection, and the top cap; or(d) the housing including, or being, the casing, along with theelectrolyte component, the conductive member, and the optional butpreferably fibrous material included therein, the tip housing and tip,and the electrical contact that is electrically associated with thesecond electrical contact.

The term “about,” as used herein, should generally be understood torefer to both numbers in a range of numerals. For example, “about 1 to10” should be understood as “about 1 to about 10.” Moreover, allnumerical ranges herein should be understood to include each wholeinteger within the range, i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10.

The term “substantially free,” as used herein, generally refers to nomore than about 10 weight percent, preferably no more than about 5weight percent, and more preferably no more than about 2 weight percentof the undesirable component, e.g., epoxy or resin based on the totalweight of the tip, or gel based on the total electrolyte component, asappropriate. In one more preferred embodiment, the term means no morethan about 1 weight percent, preferably no more than about 0.5 weightpercent, and more preferably no more than about 0.1 weight percent, ofthe undesired component. The term “entirely free” means no more than atrace amount of such undesired material(s) are present, e.g., as animpurity in the test apparatus or a portion thereof.

The foregoing detailed description outlines features of severalembodiments so that those of ordinary skill in the art may betterunderstand the various aspects of the present disclosure describing theinvention. Those of ordinary skill in the art should appreciate thatthey may readily use the present disclosure as a basis for designing ormodifying other testing apparatus and method details for carrying outthe same purposes and/or achieving the same advantages of theembodiments introduced herein. Those of ordinary skill in the art shouldalso realize that such equivalent details do not depart from the spiritand scope of the present disclosure, and that they may make variouschanges, substitutions and alterations herein without departing from thespirit and scope of the present disclosure. In the drawings, the same orsimilar elements are denoted by the same or similar reference numeralseven though they are depicted in different figures.

1. A method for analyzing an impurity content of a precious metal sample, which method comprises: associating an electrically conductive zone of a portable testing device with the sample, wherein the electrically conductive zone is detachable from the remainder of the testing device and is replaceable, and the conductive zone contains a conductive member that extends at least partially through the conductive zone; measuring the electrical resistance of one or more impurities in the sample; and comparing the measured resistance to a standard value of electrical measurements including at least one of the same type of precious metal to determine the impurity content of the sample.
 2. The method of claim 1, which further comprises displaying the measured resistance to a user.
 3. The method of claim 2, wherein displaying the measured resistance comprises transmitting electrical signals via the conductive member to a meter that is electrically coupled thereto and that compares the measured resistance to the standard value.
 4. The method of claim 1, which further comprises displaying a level of purity of the precious metal sample to a user.
 5. The method of claim 1, which further comprises removing at least a portion of a contaminant component from a surface of the sample before measuring.
 6. The method of claim 1, wherein the electrically conductive zone comprises components that are at least substantially corrosion resistant.
 7. The method of claim 1, wherein the precious metal sample contains at least a 6K gold content.
 8. The method of claim 1, which further comprises storing the measured resistance electronically for later review.
 9. The method of claim 1, which further comprises replacing the electrically conductive zone when an electrolyte contained therein is depleted.
 10. The method of claim 1, wherein the electrically conductive zone comprises an electrolyte component.
 11. The method of claim 10, which further comprises replacing the electrically conductive zone with another electrically conductive zone that contains at least one different electrolyte in the electrolyte component.
 12. The method of claim 1, wherein associating an electrically conductive zone of a portable testing device with the sample comprises contacting the device at multiple contact points along the sample simultaneously.
 13. The method of claim 1, wherein measuring the electrical resistance of the sample comprises transmitting electrical signals from the conductive zone to a test meter.
 14. The method of claim 13, wherein the test meter registers a low resistance when there are relatively no impurities present in the sample.
 15. The method of claim 1, wherein the method for analyzing an impurity content of a precious metal sample is employed multiple times sequentially on the same sample or different precious metal samples.
 16. A method of assembling a portable precious-metal testing apparatus comprising: providing a replaceable cartridge that comprises an electrolyte component therein; positioning a first end of the replaceable cartridge in a hand-held housing that is electrically associated with the remainder of the testing apparatus so that a fiber tip disposed at a second, opposite end of the replaceable cartridge protrudes from the housing; and securing the hand-held housing so as to retain the replaceable cartridge and minimize the loss of electrolyte component.
 17. The method of claim 16, wherein the housing is replaceable.
 18. The method of claim 16, wherein an electrically conductive member is disposed along a portion of the replaceable cartridge at the first end thereof and electrically associates with an electrical contact in the housing without loss of the electrolyte component.
 19. The method of claim 16, wherein the electrolyte fills a central chamber of the replaceable cartridge and is retained therein so as to avoid loss of the electrolyte component except through the fiber tip.
 20. The method of claim 16, wherein the tip is at least substantially free of epoxy or resin. 